[willamette-fcst] Forecast - Monday, March 23rd, 2009

[Willamette Valley Ag/Burning Forecast]

Daily Smoke Management Forecast




Oregon Department of Agriculture
Smoke Management Program
Weather Outlook and Field Burning Advisory for Willamette Valley Growers and Fire Districts.

Issued: 
     Monday, March 23rd, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 4:30pm.
     Straw stack burning is allowed from now until 4:30pm.

Weather Discussion:
     A cold upper-level trough moved over the Pacific Northwest
     thsi past weekend and brought widespread shower activity wit
     snow levels below the Cascades passes.  Precipitation
     amounts over the weekend were heaviest in the mountains, due
     to upsloping westerly flow aloft.  Timberline Lodge, on Mt.
     Hood, received 13 inches of snow in the past 72 hours, with
     almost a foot in the past 24 hours.  Mt. Hood Meadows
     received 4 inches of new snow in the past 24 hours.  Only
     about 2 inches of snow fell over Santiam pass last night,
     but Willamette pass picked up 8 inches of new snow overnight.

     The coldest air aloft with this system moved in Sunday
     evening, with he snow level dipping to about 1000 feet
     Sunday night. About one-half inch of snow was reported at
     just 1100 feet, near Gates, on Hwy 22 east of Salem this
     morning.  The freezing levels over Salem and Medford were
     measured at just 2500 and 2100 feet repectively early this morning.

     Rainfall in the lowlands was heaviest at the coast and
     across southwestern Oregon this past weekend.  Amounts along
     the coast ranged from about one-quarter of an inch north to
     three-quarters of an inch south.  Much of southwesterln
     Oregon picked up about one-quarter to one-third of an inch. 
     Lighter amounts of rain and some hail fell in the Willamette
     Valley, with amounts around one-tenth of an inch common. 
     The south valley, near Eugene, locally picked up more than
     one-quarter of an inch of rain.

     Showers tapered off overnight with clearing skies allowing
     temperatures to locally fall below freezing across western
     Oregon.  Hillsboro dropped down to 29 degrees, and Eugene
     dipped to 31.  Medford, in southwestern Oregon, dropped to
     28 degrees.  Middle and high clouds were increasing, at
     mid-morning, ahead of a warm front approaching the
     Washington and Oregon coast.  The ODA surface analysis
     showed increasing sotuherly pressure gradients, and south
     winds were picking up in the 5-15 mph range in the
     Willamette Valley.

     Light rain will move onto the coastline later this morning
     and into the Willamette Valley early this afternoon. 
     Southerly winds will continue to increase and may become
     blustery this afternoon, especially along the coast, where
     gusts to 45 mph are possible.  Gust to near 30 mph are
     possible this afternoon in the Willamette Valley.  Cloudy
     skies and increasing rain will cap high temperatures in the
     upper 40s, close to 10 degrees below average.  Snow levels
     will stay below the Cascade passes with several inches of
     new snow likely later today and tonight.  Valley rainfall
     amounts should be between one-tenth and one-quarter of an
     inch late this afternoon through tonight.

Surface Winds:
     SSE 10-20 this morning, S 10-20 G30 this afternoon.
Transport Winds:
     S 20 this morning, S 30 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3500 feet.  Ventilation index 105.
High Temperature:
     Salem\'s high temperature today will be near 48.
Humidities:
     Minimum relative humidity will be near 60%.
Sunrise/Sunset:
     Salem sunset tonight: 7:29pm; sunrise tomorrow: 7:07am.

Extended Outlook:
     A cold front will move across western Oregon tonight with
     some showers continuing on Tuesday.  snow levels will lift
     to about 4000 feet Tuesday afternoon, and valley highs will
     climb closer to normal.  Another system will drop int the
     region, from the northwest, Tuesday night and Wednesday,
     with more valley rain and higher elevation snow.  Snow
     levels should hold around 4000 feet.

     A trasitory ridge is forecast to bring some drying Thursday.
     A weak system is forecast to brush by the northern sections
     of Oregon Friday afternoon and night.  A cool northwesterly
     flow aloft is forecast for next weekend with a continued
     slight chance of showers...mainly north.  The ridge may
     build into the coastline enough for drying and warming early
     next week.

Tue (24 Mar):  Mostly Cloudy.  Chance of Showers.  Snow Level Rising to 4000 Feet.  40/54

Wed (25 Mar):  Rain Likely.  Snow Level 4000 Feet.  40/52

Thu (26 Mar):  Partly Sunny.  Snow Level 5000 feet.  37/56

Fri (27 Mar):  Slight Chance of Rain...Mainly North.  Snow Level 5000 Feet.  35/55

Sat (28 Mar):  Mostly Cloudy.  Slight Chance of Showers...Mainly North.  37/56

Sun (29 Mar):  Mostly Cloudy.  Slight Chance of Showers...Mainly North.  38/57

Mon (30 Mar):  Partly Cloudy.  38/60

ODA Meteorologist
weather at oda.state.or.us